4
In our demonstration of our product in the lab, no interface to the PSTN takes place.
Instead the communication is strictly between two IP nodes sending packetized voice to
and from each other (full duplex) over a wireless medium using an AdHoc networking
architecture with a CSMA/CD Medium Access Control scheme. Ad Hoc networking
involves different nodes in the network communicating without an intermediary. For
purposes of demonstrating the product we have had both wavelan cards communicating
on the same channel (3). It remains to be seen whether forcing the cards to use different
channels will degrade or improve the network performance.
3.3 OPENH323
Openh323 is an open source software implementation of the International
Telecommunication Union’s H.323 protocol which includes packet-based multimedia
communication, call control protocol, security, and media control protocol. The standard
also provides for codecs to digitize traditionally analog data such as audio and speech.
The freely downloadable simph323 is one application that implements these protocols.
The documentation relating to this protocol can be accessed at
http://www.itu.int/itudoc/itu-t/rec/h/ .
The H.323 provides foundation for audio, video, and data over IP based network. The
potential applications are:
1. Internet Telephony & Video Telephony
2. Desktop videoconferencing
3. Collaborative computing
4. Business conference calling
5. Distance learning
6. Interactive Shopping
4. EQUIPMENT:
The right choice of equipment for our product was critical for the success of our
application. Since our product involves the interworking of hardware, software, network
interface, and user interface, a misinformed or badly informed choice of any one of these
would severely affect and hamper the performance of the other parts and consequently
that of the whole. As we found out later, despite our best efforts, we were unable to
predict some of the variables.
4.1 HARDWARE
The main considerations for the hardware platform were:
(i) ability to run Linux and x86 compatible.
(ii) on-board full duplex sound support (Mic in, speaker out)
(iii) PCMCIA support for Wavelan cards
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